Many scientific, medical and industrial tasks involve the deployment of objects or instruments, which may need to be held aloft and manipulated in space for extended periods of time, resulting in repetitive stress to the user. The resulting repetitive stresses are known to be a cause of work-related trauma.
For example, work-related musculoskeletal disorders have been identified as a widespread problem amongst diagnostic medical sonographers and vascular technologists. In 2006, approximately 46,000 sonographer and vascular technologist job positions existed in the United States. A representative survey reported nearly 90% of sonographers and vascular technologists complete ultrasound scans while in some form of pain. Aggravating factors for pain during procedures was reported by sonographers to include sustained and repeated twisting of the neck and body, sustained arm abduction and application of pressure on the ultrasound transducer.
In a further example, poor ergonomics within industrial settings may also adversely affect the productivity and the health and safety of workers. Heavy tools or parts may require maneuvering in repetitive or awkward motions by workers within industrial settings. Workers may also be required to maintain fixed poses for extended periods of time. To improve worker ergonomics, devices have been developed to counterbalance tools or parts. These devices counteract the force of gravity to simulate the tool floating in air and improve worker ergonomics.
In the field of diagnostic medical sonography and vascular technology, for example, previous counterbalancing arms may have used high torque motors to counterbalance the load weight creating potential harm for a patient. In the event of a malfunction, the motors may potentially drive the arm into the patient with a minimum force of twice the weight of the arm. In the event of a power failure, a traditional arm may lose its pose and slump under its own weight as the motors can no longer counterbalance the weight. While brakes may have been applied to prevent traditional arms from slumping in a power failure, the traditional arm may become fully locked (i.e., un-adjustable) until power is restored.
Prior attempts, if any, to solve problems associated with prior art devices and/or methods may have been unsuccessful and/or had one or more disadvantages associated with them. Prior art devices and/or methods have been ill-suited to solve the stated problems and/or the shortcomings which have been associated with them.
Various prior art counterbalance systems have attempted to reduce the many aggravating factors reported by workers in the above-noted fields, including United States Patent Application No. 2010/0319164 for Counterbalance Assembly to Bax et al. (discloses a spring counterbalance system only for a single rigid arm or link) and Bax, Jeffrey et al., in Med. Phys., vol 35, no. 12, pp 5397-5410, 2008 entitled Mechanically Assisted 3D Ultrasound Guided Prostate Biopsy System.
In addition, there may be a number of known articulating arms that are configured to support a device of varying masses, but most have significant drawbacks. Some of these known arms may use a coiled spring having a fixed uniform spring rate as described in U.S. Pat. No. 8,066,251. In these arms, when the mass is varied, the coiled spring assembly disadvantageously may not be adjustable and a swap may need to be made between devices as well changing the internal component of an articulating arm (i.e., the spring). Many of these arms may also use a spring-cable-pulley system; particularly with arms consisting of a series of interconnecting links as the type that may be described in U.S. Pat. Nos. 5,435,515, 7,618,016, and 7,837,674. Previously, it may also have been known to use torsion springs in joints of the arm to generate torque forces which counter the torque loads in the joints of the arm. Furthermore, the concept of using a combination of springs and weights to counterbalance a payload may have been known as described in published U.S. Application No. 2005/0193451. A link assembly for a robot arm or snake arm consisting of two or more link members/segments in series that can be manipulated to flow axially along its length to guide a segment end to a given location may be known as described in U.S. Pat. No. 7,543,518. Also, a counterbalanced set-up arm to support a robot arm comprised of multiple joint arms, including a linkage and spring-cable-pulley balancing mechanism may also have been known as taught by U.S. Pat. No. 7,837,674.
Accordingly, there is a need for an improved counterbalancing assembly for an arm. What is needed is a counterbalance apparatus and/or method that overcomes one or more of the limitations associated with the prior art. It may be advantageous to provide an apparatus and/or method which allow the user to quickly pick up a payload with minimal effort.
It is an object of the present invention to obviate or mitigate one or more of the aforementioned disadvantages and/or shortcomings associated with the prior art, to provide one of the aforementioned needs or advantages, and/or to achieve one or more of the aforementioned objectives of the invention.